Lubricants containing benzothiadiazole



nited States Patent U.S. Cl. 25247.5 5 Claims ABSTRACT OF THE DISCLOSURE Lubricating oil compositions provided extreme pressure and wear-inhibiting properties by minor amounts of 1,2,3- benzothiadiazoles.

BACKGROUND OF THE INVENTION Field of the invention In lubricating oils, particularly ash-free or low ash lubricating oils, used in internal combustion engines, it is common to add antioxidant and antiwear agents. It is, in particular, usual to add metal salts, particularly zinc salts, of various phosphorodithioic acid esters for this purpose. However, there have been continual efforts to reduce the amount of metal in lubricating oils, as these metals in ionic form frequently enhance deposit formation during service. It has thus been wished to provide antiwear and antioxidant materials which do not provide undesirable metal ions.

-It has been further desired to provide lubricants which possess extreme pressure characteristics, e.g., to reduce Wear on bearings, etc. when they are subjected to the application of large forces. This has been accomplished with the use of various additives, particularly chlorine substituted organic compounds such as chlorinated waxes.

Description of the prior art SUMMARY OF THE INVENTION Lubricating compositions are provided comprising a major proportion of an oil of lubricating viscosity and a minor proportion, sufiicient to provide wear, corrosion inhibiting and extreme pressure properties, of 1,2,3- benzothiodiazole or its chlorinated analogs. Thus the additives of this invention are the following formula:

in which X is chlorine and n=04.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 1,2,3-benz0thiadiazole is well known as a dye intermediate. Its preparation is, therefore, well known in the art. The compound can be produced by the reaction of 2-aminothiophenol with nitrous acid or with nitrosylsulfuric acid. A representative chlorine-substituted material may be prepared by the reaction of 2,2-dithio-bis- (5-ch1oroaniline), a commercially available material with nitrosyl sulfuric acid.

In general, in reacting with nitrosyl sulfuric acid, the temperature of the reaction mixture is kept low, preferably not above 5 C.

The lubricating oils in which the benzothiadiazoles are used may be derived from natural or synthetic sources. Lubricating oils generally have viscosities of from about 35 to 50,000 Saybolt Universal Seconds (SUS) at F. Among natural hydrocarbonaceous oils are paraffinic base, naphthenic base, asphaltic base and mixed base oils. Illustrative synthetic hydrocarbonaceous oils are polymers of various olefins, generally of from 2 to 8 carbon atoms and alkylated aromatic hydrocarbons.

The benzothiadiazoles are preferably compounded with from 1 to 15 Weight percent of a polylalkylene polyamine lubricating oil detergent. These detergents are described in U.S. Pats. 3,219,666 and 3,202,678. The polyalkylene polyamines will generally have from 2 to 6 nitrogen atoms and alkylene groups of from 2 to 3 carbon atoms. Bonded to the alkylene polyamines will generally be from 1 to 2 oil soluble aliphatic hydrocarbon groups, usually a polymer of olefins of from 3 to 4 carbon atoms (propene and isobutylene). The hydrocarbon groups are bonded to the alkylene polyamine directly to nitrogen or through a nonoxocarbonyl group such as formyl or succinoyl. The aliphatic hydrocarbon group will generally be of from 30 to 200 carbon atoms, more usually of from 50 to 150 carbon atoms.

Other additives may also be present, such as antirust agents, corrosion inhibitors, other detergents, additional oxidation inhibitors, oiliness agents, etc.

The 1,2,3-benzothiadiazoles will generally be present in from 0.1 to 10.0% by weight of lubricating oil compositions, more usually from about 0.5 to 5.0% by weight. The other additives will generally be present individually in from about 0.01 to 15 weight percent, more usually from about 0.05 to 10 weight percent. The alkylene polyamine detergent will usually be present in from 2 to 15 weight percent.

The following examples are offered by way of illustration and not by way of limitation.

Example I.Preparation of 1,2,3-benzothiadiazole: 60 g. (0.44 moles) of 2-aminothiophenol was mixed with 50 ml. of 'water in a 500 ml. flask. A solution of 25 ml. of sulfuric acid in ml. H O was cooled to 0 C. and added slowly with stirring to the reaction flask, the contents of which were likewise cooled to 0i2 C. An ice cold solution of sodium nitrite (34 g. in 50 ml. H O) was added dropwise as a slurry to the reaction flask over a period of four hours while the temperature of the mixture was maintained at 2i2 C. The solid material which precipitated from the reaction mixture was filtered from the mixture and steam distilled. The product was then dried in a desiccator over NaOH.

Example II.Preparation of 6-chloro-1,2,3-benzothiadiazole: To 197 cc. of concentrated H 80 cooled to 0 C. was slowly added 28.4 g. of sodium nitrite. The mixture was stirred for 15 min., heated to 70 C. and cooled to 10 C.

50.0 g. of 2,2-dithio-bis-(S-chloroaniline) was dissolved in 134 ml. of concentrated H SO at room temperature with stirring. The mixture was then cooled to 0 C.

The second solution was added dropwise to the first with stirring over a period of 30 min. The mixture was then allowed to stand for 30 minutes and then poured into a liter of mixed ice and Water. The mixture foamed and emitted a brown vapor. It was allowed to stand over the weekend.

The solids were filtered from the mixture, dissolved in ether, and washed twice with Water. The ether solution was dried with sodium sulfate and stripped, the residue being redissolved in toluene, from which it was recrystallized and then dissolved in mixed hexane, dried and stripped. The yield was 14.6 g. of a brownish solid having a melting range of 102.5-104 C. This material was then dissolved and recrystallized from an ethanol water mixture.

The residues were collected, stripped and chromatographed over silica gel with mixed hexanes and recrystallized from ethanol water mixture yielding 11 g. more for a total yield of 21 g. of 6-chloro-1,2,3-benzothiadiazole.

In order to demonstrate the excellent effectiveness of the benzothiadiazoles utilized in the lubricating oils of this invention in imparting EP and antiwear properties to lubes, a number of industry-recognized tests were performed.

To demonstrate the effectiveness of the lubricating oils under extreme pressure conditions, the oils were tested in the Falex Shear Test, results of which may be found in Table I following. The results are reported as load at failure in pounds.

TABLE I Formulation: Load at failure, lbs. Base oil 1 850 Base oi1+0.5% 1,2,3-

benzothiadiazole 1375 Base oil+1.0% 1,2,3-

benzothiadiazole 1700 Base oil+2.5% 1,2,3-

benzothiadiazole 2780 Base oil+1.0% 4-chloro- 1,2,3-benzothiadiazole 1055 Base oil+2.0% 4-chloro- 1,2,3-benzothiadiazole 1985 480 neutral oi1+5 weight percent polyisobntenyl succinimide of tetraethylene pentamine (polyisobutenyl-'1000 mol. wt.) and 0.1 weight percent terephthalic acid (corrosion inhibitor).

These data show the effectiveness of 1,2,3-benzothiadiazole in increasing load to failure, by a factor of over 3:1 compared to the base oil alone, when the additive is employed at 2.5% concentration.

In order to demonstrate the degree of protection provided to copper and lead bearing material by the compositions of this invention, copper and lead strips were immersed in oil formulation employing the same base oil and detergent additive as in the Falex Test. The immersion was continued at a temperature of 340 F. for

20 hours. During the heating period, the oil is vigorously 5 stirred. At the end of the test period, the strips are removed and weight loss is determined. The copper strip is washed with KCN to remove copper salts which may form on the surface. The results may be found in the following table:

TABLE II.COPPER-LEAD STRIP CORROSION TEST Additive Weight loss, mg.

Concen- Cu tration, wt. Before After Type percent Pb KCN KCN (Base oil) 928 12. 4 15. 6 1, 2, 3-benzothiadiazo1e 0. 2 855 22. 2 25. 3 1. 0 557 9. 5 15. 1

in which X is chlorine and n is 0-4.

2. A lubricating oil composition according to claim 1 in which n is 0.

3. A lubricating oil composition according to claim 1 in which the extreme pressure additive is 1,2,3-benzothiadiazole.

4. A lubricating oil composition according to claim 1 having from 2-15 weight percent of an alkylene polyamine of from 2 to 6 nitrogen atoms, wherein the alkylene groups are from 2 to 3 carbon atoms, having bonded to nitrogen of from 12 oil soluble aliphatic hydrocarbon groups of from 30 to 200 carbon atoms, wherein said aliphatic hydrocarbon groups are bonded to nitrogen either directly or through a nonoxocarbonyl group.

5. A lubricating oil composition according to claim 2 where the additive is present in the amount of from about 0.5 to 5.0 percent by weight.

References Cited UNITED STATES PATENTS 2,154,097 4/1939 Loane 252--47.5 2,218,283 10/1940 Fuller 25247 FOREIGN PATENTS 972,388 7/ 1959 Germany.

DANIEL E. WYMAN, Primary Examiner J. M. HICKEY, Assistant Examiner US. Cl. X.R. 252-47, 391 

